The National Osteoporosis Risk Assessment (NORA) is a public health initiative that will create a longitudinal, observational data base of as many as 500,000 post-menopausal women. The data collected from these patients will offer opportunities to conduct longitudinal research to examine the relationship between risk factors for osteoporosis including low bone mineral density and patient outcomes such as changes in BMD and fracture risk. The initial objective is to determine the relationship between BMD measurements at each of a number of skeletal sites and a patient's long and short term risk of fracture. This analysis will attempt to determine the incremental predictive value of each of the measurements as well as identify combinations of BMD measures that, when considered in conjunction with other risk factor information, offer a more predictive and cost-effective method of evaluating a patient's overall risk of fracture.